Earthboring tool and method of casehardening

ABSTRACT

A method of casehardening an earthboring tool component includes steps of providing an earthboring tool component and providing a semiconductor light emitting device carried by a mechanical arm. The mechanical arm is used to move the semiconductor light emitting device relative to the earthboring tool component. Light emitted by the semiconductor light emitting device is directed to a surface of the earthboring tool component so that it is casehardened.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates generally to earthboring tools for cutting earthen annulus.

2. Description of the Related Art

Earthboring tools are commonly used to bore holes by cutting through earthen annulus. Such holes may be bored for many different reasons, such as drilling for oil, minerals and water. One type of earthboring tool used for boring is a rotary earth bit. Several examples of rotary earth bits are disclosed in U.S. Pat. Nos. 3,550,972, 3,847,235, 4,136,748, 4,427,307, 4,688,651 and 4,741,471. A rotary earth bit generally includes one or more earth bit cutting cones rotatably mounted to corresponding lugs with a hub unit, as well as ball and roller bearings. The lugs generally form a portion of an earth bit body and, as the earth bit body rotates, the cutting cone rotates in response to contacting earthen annulus.

Another type of earthboring tool is a mechanized boring cutter, with an example being disclosed in U.S. Pat. No. 4,040,493. A mechanized boring cutter generally includes a hub unit rotatably mounted to a shaft and a cutting cone frictionally engaged with the hub unit. The hub unit is often rotatably mounted to the shaft using ball bearings.

It is known that earthboring tools wear out with use. As a result, they are often casehardened to reduce the amount of wear they experience. Examples of casehardened earthboring tools are disclosed in U.S. Pat. Nos. 4,303,137, 4,627,882, 4,643,051, 4,660,444 and 4,781,770. Casehardening sometimes involves subjecting the earthboring tool to a carburization process. However, there are several problems with using a carburization process.

A carburization process is typically a “batch process”, wherein a number of earthboring tool components are heated by a large and expensive furnace at the same time. The components are heated at the same time because it is not economical, or otherwise beneficial, to heat fewer components using a carburization process. Since the components are heated at the same time, they are casehardened in the same way without providing an option for selective casehardening. Further, the region of the earthboring tool component that is casehardened is often casehardened non-uniformly so its hardness undesirably varies from one location to another.

The carburization process also requires a long period of time. The furnace can provide temperatures in excess of 1700° F., resulting in a carburization process that can take ten or more hours. After the earthboring tool component is heated by the furnace, it is generally slow cooled, quenched and machine finished, which requires additional time.

Another problem is that the earthboring tool components typically include low alloy carbon steel, wherein the amount of carbon is generally less than one-quarter of one percent. Low alloy carbon steel often wears down faster than higher alloy carbon steel, so low alloy carbon steels are often case carburized to allow them to function with acceptable wear in earthboring tools. During the case carburizing process, the amount of carbon in the surface of the steel is increased by introducing an expensive carbon rich gas into the atmosphere in the furnace when the batch of earthboring tool components is being heated.

Other methods of casehardening involve using gas lasers that emit light or electron emitters that emit electrons. However, gas lasers and electron beam emitters are expensive and difficult to accurately align with the earthboring tool. They are difficult to align because they are unwieldy and the alignment often requires mirrors. Hence, it is desirable to provide other casehardening methods that are simpler, more time efficient and less costly.

BRIEF SUMMARY OF THE INVENTION

The present invention provides a method of casehardening an earthboring tool component. The method includes steps of providing a first earthboring tool component and a semiconductor light emitting device carried by a mechanical arm. The method also includes a step of directing light emitted by the light emitting device to a first surface of the first earthboring tool component, wherein the first surface is casehardened in response to being heated by the light. The properties of the light are chosen so that the amount of time needed to caseharden the first earthboring tool component is significantly reduced.

In some situations, the light emitting device is moved, using the mechanical arm, so that a second surface of the first earthboring tool component is exposed to the light and casehardened in response. In some situations, the first earthboring tool component is moved so the light is provided to the second surface. In this way, selected surfaces of the first earthboring tool component are casehardened.

In some embodiments, the first earthboring tool component is replaced with a second earthboring tool component. In this way, the first and second earthboring tool components can be casehardened separately and provided with different amounts of casehardening. The second earthboring tool component is exposed to light emitted by the light emitting device so that a surface of it is casehardened. The first and second earthboring tool components can be coupled together to form an earthboring tool. The first and second earthboring tool components are often coupled together so that their casehardened surfaces face each other. In this way, these surfaces experience less wear when they engage each other.

These and other features, aspects, and advantages of the present invention will become better understood with reference to the following drawings and description.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1 a and 1 b are side views of a semiconductor light emitting device carried by a mechanical arm and directed at an earthboring tool component, in accordance with the invention.

FIG. 2 a is a perspective view of a rotary earth bit which can be casehardened, in accordance with the invention.

FIG. 2 b is a cross-sectional view taken along a cut-line 2 b-2 b of the earth bit of FIG. 2 a.

FIG. 2 c is a more detailed view of a cutting cone and hub unit included with the rotary earth bit of FIG. 2 a.

FIG. 2 d is a more detailed view of the cutting cone of FIG. 2 c with the hub unit removed from it.

FIG. 2 e is a more detailed view of the hub unit of FIG. 2 c removed from the cutting cone.

FIG. 3 is a side view of an earthboring tool embodied as a mechanized boring cutter.

FIGS. 4, 5 and 6 are perspective views of an earthboring tool casehardening system, in accordance with the invention.

FIG. 7 is a flow diagram of a method of casehardening an earthboring tool component, in accordance with the invention.

FIGS. 8 and 9 are flow diagrams of methods of assembling an earthboring tool, in accordance with the invention.

DETAILED DESCRIPTION OF THE INVENTION

FIGS. 1 a and 1 b are side views of a semiconductor light emitting device 100 carried by a mechanical arm 101. In accordance with the invention, light emitting device 100 is carried by mechanical arm 101 so it is directed at an earthboring tool component 105. Semiconductor light emitting device 100 can be of many different types, but, in this embodiment, it is a laser diode. A laser diode is much smaller than a gas laser and an electron beam emitter, so it can be easily moved from one position to another. Further, a laser diode generally uses less power and requires less cooling than a gas laser and electron beam emitter. Mechanical arm 101 can be of many different types, such as those found in U.S. Pat. Nos. 4,545,713, 4,626,999, 4,892,992 and 6,920,375. Earthboring tool component 105 can be a component of many different types of earthboring tools, a few of which will be discussed in more detail below with FIGS. 2 a and 3.

In accordance with the invention, mechanical arm 101 moves light emitting device 100 in a controlled manner relative to earthboring tool component 105. The manner in which mechanical arm 101 moves device 100 can be controlled in many different ways, such as with a computer system (not shown). For example, mechanical arm 101 can be used to move the position of light emitting device 100 along a predetermined path relative to earthboring tool component 105 in response to one or more control signals from the computer system.

In accordance with the invention, light emitting device 100 is repeatably moveable, by using mechanical arm 101, between many different positions relative to earthboring tool component 105. A few of these positions are denoted as Positions A, B, C, D and E in FIGS. 1 a and 1 b. In Position A, light emitting device 100 is directed at earthboring tool component 105 so its optical path extends along a reference line 109 a. Light emitting device 100 emits light 104, as indicated by an indication arrow 108, so that light 104 is directed along its optical path. In this embodiment, reference line 109 a intersects a surface 106 of earthboring tool component 105, wherein surface 106 is flat so that reference line 109 a is oriented perpendicular to it. However, it should be noted that surface 106 can have many other shapes, such as curved, but it is shown here as being flat for simplicity.

In this embodiment, Positions B and C correspond to light emitting device 100 being positioned so that its optical path is directed along reference lines 109 b and 109 c, respectively. Reference lines 109 b and 109 c are parallel to reference line 109 a, so that they are also perpendicular to surface 106. Light emitting device 100 is moveable between Positions A, B and C by moving it, using mechanical arm 101, in opposed directions indicated by a direction arrow 102 a.

Light emitting device 100 is positioned by mechanical arm 101 so that reference lines 109 a, 109 b and 109 c extend a distance d between light emitting device 100 and surface 106. However, in accordance with the invention, light emitting device 100 is repeatably moveable, in response to moving mechanical arm 101, in opposed directions towards and away from surface 106, as indicated by a direction arrow 102 b. In this way, distance d is adjustable in response to adjusting the position of light emitting device 100 with mechanical arm 101.

It should be noted that, in this example, the movement of light emitting device 100 in directions 102 a and 102 b corresponds to linear movement because the angles between reference lines 109 a, 109 b and 109 c do not change relative to each other. Further, in this embodiment, the angles between reference lines 109 a, 109 b and 109 c do not change relative to surface 106 because it is flat, as mentioned above.

As indicated by indication arrow 108, light emitting device 100 emits light 104 so it flows along reference line 109 a and is incident to surface 106 and forms a light receiving region 107. A light receiving region can also be formed where reference lines 109 b and 109 c intersect surface 106, such as when light emitting device 100 is in Positions B and C, respectively. However, light receiving regions from device 100 being in Positions B and C are not shown here for simplicity. The area of light receiving region 107 generally depends on many different factors, such as the shape of the beam of light emitted by light emitting device 100. The area of light receiving region 107 also depends on the angle of the optical path of device 100 relative to surface 106, as will be discussed in more detail presently.

As shown in FIG. 1 b, mechanical arm 101 can move light emitting device 100 to many other positions, a few of which are denoted as Positions D and E. In Positions D and E, the optical path of light emitting device 100 extends along reference lines 109 d and 109 e, respectively. Reference lines 109 d and 109 e are at angles θ₁ and θ₂, respectively, relative to reference line 109 a, and intersect surface 106 proximate to the same location as reference line 109 a. In this example, a light receiving region 107 a corresponds to light 104 incident to surface 106 from reference line 109 a and a light receiving region 107 b corresponds to light 104 incident to surface 106 from reference lines 109 d and 109 e.

It should be noted that angles θ₁ and θ₂ correspond to the angle of incidence of the optical path of light emitting device 100. The angle of incidence increases as angles θ₁ and θ₂ increase and the angle of incidence decreases as angles θ₁ and θ₂ decrease. As the angle of incidence increases the area of the light receiving region increases. Further, as the angle of incidence decreases the area of the light receiving region decreases. In this way, light receiving region 107 b has a greater area than light receiving region 107 a and light receiving region 107 a has a smaller area than light receiving region 107 b.

Mechanical arm 101 moves light emitting device 100 in opposed directions indicated by a direction arrow 102 d when moving light emitting device 100 between Positions A and D. Further, mechanical arm 101 moves light emitting device 100 in opposed directions indicated by a direction arrow 102 e when moving light emitting device 100 between Positions A and E. It should be noted that, in this example, the movement of light emitting device 100 in directions 102 d and 102 e corresponds to angular movement because the angles between reference lines 109 a, 109 d and 109 e change relative to each other. Hence, as shown in FIGS. 1 a and 1 b, light emitting device 100 can be linearly and angularly moved, using mechanical arm 101, between different positions relative to earthboring tool component 105. It should be noted that earthboring tool component 105 can also be moved relative to light emitting device 100 and mechanical arm 101, as will be discussed in more detail with FIGS. 4, 5 and 6.

Earthboring tool component 105 generally includes steel, which can have many different grades. In accordance with the invention, the grade of steel included with component 105 is chosen to include approximately 0.40% carbon, although more carbon can be included in other embodiments. This amount of carbon is generally larger than that used in earthboring tool components subjected to the carburization process. The amount of carbon included in the steel is chosen to obtain a desired amount of case hardening in response to being exposed to light 104. To provide the desired amount of casehardening, the amount of carbon included in the steel can be less if the time the steel is exposed to light 104 is increased. Further, to provide the desired amount of casehardening, the amount of carbon included in the steel can be more if the time the steel is exposed to light 104 is decreased.

The portions of earthboring tool component 105 below light receiving regions 107, 107 a and 107 b are heated and casehardened in response to receiving light 104. For example, portions of earthboring tool component 105 at a depth below surface 106 and within or proximate to light receiving regions 107, 107 a and 107 b, are heated and casehardened. The depth below surface 106 that is casehardened is often referred to as the case depth. More information regarding casehardening can be found in U.S. Pat. Nos. 4,643,051 and 4,660,444.

Using light emitting device 104 to caseharden earthboring tool component 105 is useful because component 105 can be casehardened in a less amount of time. For example, the carburization process can take ten or more hours to caseharden component 105. However, component 105, or portions thereof, can be casehardened sufficiently enough within tens of seconds to one or more minutes.

The amount of casehardening provided to earthboring tool component 105, as well as the case depth, can be controlled in many different ways. For example, light 104 emitted by semiconductor light emitting device 100 can have many different amounts of power. However, an amount of power in a power range between about two kilowatts and six kilowatts was found to be useful in casehardening surface 106 sufficiently. As the amount of power in light 104 increases, more casehardening is provided because the temperature of surface 106 increases more. If the amount of power in light 104 increases less, then less casehardening is provided because the temperature of surface 106 increases less. In this way, the amount of casehardening provided to earthboring tool component 105 can be controlled by controlling the amount of power of light 104.

The amount of optical power of light 104 provided to surface 106 can be adjusted in response to adjusting the position of light emitting device 100 relative to the earthboring component with mechanical arm 101. The amount of power of light 104 can be adjusted because it depends on the position and orientation of light emitting device 100 relative to earthboring tool component 105. For example, the power can be adjusted by adjusting distance d. As distance d decreases, the power provided to surface 106 increases because there are fewer optical losses experienced by light 104. As distance d increases, the power provided to surface 106 decreases because there are more losses experienced by light 104. In this way, the distance between laser 100 and surface 106 can be adjusted, with mechanical arm 101, to adjust the amount of casehardening provided to earthboring tool component 105.

The amount of optical power, and hence the amount of casehardening provided to earthboring tool component 105 can also be controlled by controlling the intensity of light 104. The intensity of light 104 within the light receiving region can be controlled in many different ways, such as by controlling angles θ₁ and θ₂. As angles θ₁ and θ₂ increase, the intensity of light 104 decreases because the angle of incidence is larger and the light receiving region is larger. Further, as angles θ₁ and θ₂ decrease, the intensity of light 104 increases because the angle of incidence is smaller and the light receiving region is smaller. In general, earthboring tool component 105 is casehardened more in response to more intense light because the temperature of surface 106 is increased more. Further, earthboring tool component 105 is casehardened less in response to less intense light because the temperature of surface 106 is increased less.

The area of the light receiving region is related to the power density of light 104 on surface 106. Hence, the amount of casehardening provided to earthboring tool component 105 can be controlled by controlling the power density of light 104. The area of the light receiving region depends on the angle of incidence, as discussed above. As the area of the light receiving region decreases, the power density increases and, in response, the temperature of surface 106 increases more. Further, as the area of the light receiving region increases, the power density decreases, and, in response, the temperature of surface 106 increases less. In this way, the angle of incidence of light 104 can be adjusted, with mechanical arm 101, to control the amount of casehardening provided to earthboring tool component 105.

Semiconductor light emitting device 100 generally has many different modes of operation. For example, light emitting device 100 can be operated in a pulsed mode or a continuous mode of operation. In the continuous mode, the output power of device 100 is substantially continuous and, in the pulsed mode, the power output of device 100 is alternately increased and decreased. In general, more power is provided to surface 106 when light emitting device 100 is operated in a continuous mode of operation and less power is provided to surface 106 when device 100 is operated in a pulsed mode of operation. In this way, the amount of casehardening provided to earthboring tool component 105 can be controlled by controlling the mode of operation of semiconductor light emitting device 100.

It should be noted that the amount of casehardening provided by light emitting device 100 to earthboring tool component 105 can be controlled in many other ways. For example, in some embodiments, light 104 can flow through a lens before it reaches surface 106. The optical properties of the lens are chosen to provide light receiving region 107 with a desired intensity and area. In other examples, the properties of light 104 are chosen to provide a desired amount of casehardening, as will be discussed in more detail presently.

Light 104 emitted by semiconductor light emitting device 100 can have many different wavelengths. However, light 104 is generally infrared light because infrared light was found to be useful in casehardening surface 106 sufficiently. Infrared light generally has a wavelength between about 900 nanometers and about 1450 nanometers, although the wavelength can be outside of this range.

As the wavelength of light 104 decreases, it has more energy so the temperature of surface 106 increases more and more casehardening is provided. Further, as the wavelength of light 104 decreases, it is less capable of penetrating into light receiving region 107 so the case depth is less. As the wavelength of light 104 increases, it has less energy and the temperature of surface 106 increases less and less casehardening is provided. Further, as the wavelength of light 104 increases, it is more capable of penetrating into light receiving region 107 so the case depth is more. In this way, the amount of casehardening provided to earthboring tool component 105, as well as the case depth, can be controlled by controlling the wavelength of light 104.

FIG. 2 a is a perspective view of a rotary earth bit 110, in accordance with the invention. There are many different types of rotary earth bits, and examples are provided in the references discussed above in the description of the related art. In this embodiment, rotary earth bit 110 is a tri-cone earth bit having an earth bit body 120 which carries three lugs 111 and corresponding cutting cones 112.

FIG. 2 b is a cross-sectional view of lug 111 and cutting cone 112 taken along a cut-line 2 b-2 b of FIG. 2 a. FIG. 2 c is a more detailed view of cutting cone 112 and a hub unit 113 included with rotary earth bit 110 and FIG. 2 d is a more detailed view of cutting cone 112 of FIG. 2 c with hub unit 113 removed from it.

In this embodiment, hub unit 113 is attached to lug 111 and received by a channel 135 (FIG. 2 d) of cutting cone 112. In this way, lug 111 and cutting cone 112 are coupled together with hub unit 113. Cutting cone 112 is rotatably mounted to hub unit 113 with ball bearings 118 a and 118 b, as well as roller bearings 116 a, 116 b, 116 c and 116 d, so that cutting cone 112 is rotatable about an axis 119. In operation, lug 111 rotates in response to the rotation of earth bit body 120. As lug 111 rotates, cutting cone 112 rotates around hub unit 113 in response, and cuts into the earthen annulus it contacts.

Rotary earth bit 110 includes several portions that experience wear during operation. For example, lug 111 includes outer surfaces 111 a, 111 b and 111 c and cutting cone 112 includes an outer cutting surface 117 that experience wear when contacting earthen annulus. Further, cutting cone 112 and hub unit 113 often engage each other in response to external forces applied to cutting surface 117, so that the interface between cutting cone 112 and hub unit 113 experiences wear.

FIGS. 2 d and 2 e are more detailed views of cutting cone 112 and hub unit 113, respectively. Hub unit 113 includes surfaces 114 a and 114 b (FIG. 2 c) that face surfaces 115 a and 115 b (FIG. 2 d), respectively, of cutting cone 112. The outward facing surfaces of bearings 116 a, 116 b, 116 c, 116 d, 118 a and 118 b face surfaces 121 a, 121 b, 121 c, 121 d, 121 e and 121 f (FIG. 2 d), respectively, of cutting cone 112. It should be noted that surfaces 115 a-115 d and 121 a-121 f bound channel 135 of cone 112. Further, the outward facing surfaces of bearings 116 a, 116 b, 116 c, 116 d, 118 a and 118 b face surfaces 123 a, 123 b, 123 c, 123 d, 123 e and 123 f (FIG. 2 d), respectively, of hub unit 113.

The surfaces of bearings 116 a, 116 b, 116 c, 116 d, 118 a and 118 b can engage corresponding surfaces of cutting cone 112 and/or hub unit 113 in response to the external force applied to outer cutting surface 117. Further, surfaces 114 a and 114 b, 115 a and 115 b, 121 a-121 f and 123 a-123 f, as well as the outwardly facing surfaces of bearings 116 a-116 d and 118 a-118 b, often experience wear when cutting cone 112 and hub unit 113 rotate relative to each other.

FIG. 3 is a side view of an earthboring tool embodied as a mechanized boring cutter 150. In this embodiment, mechanized boring cutter 150 includes a shaft 153 around which a boring cutter header assembly 151 is rotatably coupled. Shaft 153 includes opposed end surfaces 154 and 155 and a side surface 157. Boring cutter header assembly 151 includes a hub unit 158, as indicated by an indication arrow 156, and a tapered cutting cone 152, wherein tapered cutting cone 152 includes an outer cutting surface 152 a. In accordance with the invention, any of the components of rotary earth bit 110 and mechanized boring cutter 150 can correspond to rotary earth bit component 105 of FIGS. 1 a and 1 b. Hence, any of the components of bit 110 and cutter 150 can be casehardened using an earthboring tool casehardening system, as will be discussed in more detail presently.

FIG. 4 is a perspective view of an earthboring tool casehardening system 170, in accordance with the invention. In this embodiment, earthboring tool casehardening system 170 includes a rotary system 160 operatively coupled with a shaft 161. Earthboring tool casehardening system 170 includes a motor (not shown) that operates to rotate shaft 161. In accordance with the invention, an earthboring tool component is coupled with shaft 161 so it will rotate in response to the rotation of shaft 161. In this particular example, the earthboring tool component is embodied as cutting cone 112, wherein cutting surface 117 faces upwardly and away from rotary system 160, and channel 135 (FIG. 2 d) faces downwardly towards rotary system 160.

In accordance with the invention, earthboring tool casehardening system 170 includes mechanical arm 101 which carries light emitting device 100, as described in more detail above with FIGS. 1 a and 1 b. In this embodiment, mechanical arm 101 is positioned proximate to rotary system 160 so that the optical axis of light emitting device 100 is directed at cutting surface 117 of cutting cone 112. Mechanical arm 101 can move light emitting device 100 relative to rotary system 160 and cutting cone 112. For example, mechanical arm 101 can move light emitting device 100 in directions 102 a and 102 b, as shown in FIG. 1 a. Mechanical arm 101 can also move light emitting device 100 in directions 102 d and 102 e, as shown in FIG. 1 b.

In operation, light emitting device 100 emits light 104 which is incident to surface 117. Light 104 heats surface 117 within, and proximate to, light receiving region 107. Hence, portions of cutting cone 112 proximate to and at a depth below light receiving region 107 are heated and casehardened in response to light 104. As discussed above, the depth below surface 117 that is casehardened is often referred to as the case depth. After surface 117 has been casehardened, it can be treated, such as by sanding, if desired.

It should be noted that cutting cone 112 can be rotated about axis 119, if desired, by rotating shaft 161 with the motor of rotary system 160. As cutting cone 112 rotates, light receiving region 107 moves relative to surface 117 so that the portion of surface 117 that is casehardened is increased. It should be noted that system 170 can caseharden other surfaces of cutting cone 112, one of which will be discussed in more detail presently.

FIG. 5 is a perspective view of earthboring tool casehardening system 170, wherein rotary system 160 carries cutting cone 112 so that channel 135 faces upwardly away from rotary system 160 and cutting surface 117 faces downwardly towards rotary system 160. In this embodiment, mechanical arm 101 is oriented so that light emitting device 100 is directed to an inner surface 122 within channel 135, as better seen in a cross-sectional view of cutting cone 112, which is indicated by an indication arrow 161. Inner surface 122 can correspond to many surfaces of cutting cone 112, such as surfaces 115 a and 115 b and 121 a-121 f (FIG. 2 d). Cutting cone 112 can be rotated around axis 119, if desired, by rotating shaft 161 with the motor of rotary system 160. As cutting cone 112 rotates, light receiving region 107 moves relative to surface 122 so that a larger portion of it is casehardened.

It should be noted that mechanical arm 101 can position light emitting device 100 outside of channel 135 so that its optical path 104 is directed at surface 122. However, in this example, mechanical arm 101 positions light emitting device 100 so device 100 extends into channel 135. In this way, optical path 104 of light emitting device 100 is directed at surface 122 without using mirrors.

It should also be noted that system 170 can be used to caseharden many other earthboring tool components and surfaces, such as the outer surfaces of bearings 116 a-116 d and 118 a-118 b, as well as surfaces 114 a and 114 b of hub unit 113 (FIG. 2 c). Further, mechanical arm 101 can be adjusted to move light emitting device 100 in directions 102 a and 102 b, as shown in FIG. 1 a, and directions 102 d and 102 e, as shown in FIG. 1 b. Further, system 170 can be used to caseharden other earthboring tool components, as will be discussed in more detail presently.

FIG. 6 is a perspective view of earthboring tool hardening system 170, wherein lug 111 is coupled with shaft 161 so it rotates therewith. In this way, cutting cone 112 (FIGS. 4 and 5) is replaced with lug 111. This is useful so that cutting cone 112 and lug 111 can be casehardened separately and provided with different amounts of casehardening. Lug 111 is described in more detail above with FIGS. 2 a and 2 b.

In one example, mechanical arm 101 carries light emitting device 100 so it is directed at surface 111 a of lug 111. Lug 111 is rotated so that light emitting area 107 is moved around surface 111 a to caseharden it. After surface 111 a is sufficiently casehardened, mechanical arm 101 moves light emitting device 100 in direction 102 b so it is directed at surface 111 b. Lug 111 is rotated so that light emitting area is moved around surface 111 b to caseharden it. After surface 111 b is sufficiently casehardened, mechanical arm 101 moves light emitting device 100 in direction 102 b so it is directed at surface 111 c. Lug 111 is rotated so that light emitting area 107 is moved around surface 111 c to caseharden it. When casehardening surfaces 111 a, 111 b, and 111 c, light emitting device 100 can also move in direction 102 a, 102 d, and 102 e, if necessary, as discussed above in FIGS. 1 a and 1 b.

It should be noted that mechanical arm 101 can move light emitting device 100 so it is directed at surface 111 d so that surface 111 d is casehardened. Further, it should be noted that surfaces 111 a, 111 b and 111 c can be casehardened in many other orders than the one discussed here. It should also be noted that surfaces 123 a-123 f and surfaces 114 a and 114 b of hub unit 113 can also be casehardened, if desired. In this way, the position of light emitting device 100 is moved to direct light 104 to different surfaces of lug 111.

After the desired portions of lug 111, cutting cone 112 and/or hub unit 113 are casehardened, they can be removed from system 170 and coupled together to assemble earthboring tool 110, as discussed in more detail above with FIGS. 2 a, 2 b, 2 c and 2 d. For example, surfaces 114 a and 115 a of hub unit 113 and cone 112, respectively, can be casehardened, and then hub unit 113 and cone 112 can be coupled together, as shown in FIGS. 2 c and 2 d. In this way, surfaces 114 a and 115 a face each other, respectively. In this way, surfaces from two different earthboring tool components are casehardened and positioned so they face each other. This is useful because surfaces 114 a and 115 a generally engage each other during the normal operation of rotary earth bit 110. Hence, by casehardening surfaces 114 a and 115 a, the amount of wear they experience is decreased. It should be noted that other surfaces of cutting cone 112 and hub unit 113 that face each other can also be casehardened so they experience less wear.

FIG. 7 is a flow diagram of a method 200 of casehardening an earthboring tool, in accordance with the invention. In this embodiment, method 200 includes a step 201 of providing a first earthboring tool component and a step 202 of providing a semiconductor light emitting device carried by a mechanical arm. Method 200 also includes a step 203 of directing light emitted by the semiconductor light emitting device to a first surface of the first earthboring tool component.

In some embodiments, method 200 includes a step of moving, along a predetermined path, the position of the semiconductor light emitting device relative to the first earthboring tool component. Method 200 can also include a step of moving the position of the semiconductor light emitting device to direct the light to a second surface of the first earthboring tool component. Method 200 can include a step of rotating the first earthboring tool component so the optical path of the light emitting device moves along its surface. Method 200 can further include a step of replacing the first earthboring tool component with a second earthboring tool component and repeating one or more of the steps of method 200.

In some embodiments, method 200 can also include a step of adjusting, with the mechanical arm, the distance between the semiconductor light emitting device and first surface to adjust the amount of optical power applied to the surface. Method 200 can further include a step of adjusting, with the mechanical arm, the angle of incidence of the light to adjust the case depth, as well as the amount of optical power applied to the first surface. Method 200 can also include steps of adjusting the optical power and/or frequency of the light emitted by the light emitting device. Method 200 can also include steps of adjusting the mode of operation of the light emitting device.

FIG. 8 is a flow diagram of a method 210 of assembling an earthboring tool, in accordance with the invention. In this embodiment, method 210 includes a step 211 of providing an earthboring tool which includes first and second earthboring tool components and a step 212 of rotating the first earthboring tool component. The first earthboring tool component can be rotated in many different ways, such as with an earthboring tool casehardening system.

Method 210 also includes a step 213 of directing light from a semiconductor light emitting device to a surface of the first earthboring tool component so it is casehardened. In accordance with the invention, the semiconductor light emitting device is carried by a mechanical arm. In some embodiments, method 210 includes a step of adjusting the distance between the semiconductor light emitting device and the surface by adjusting the position of the mechanical arm. Method 210 can also include a step of adjusting the angle of incidence of the light relative to the surface by adjusting the position of the mechanical arm.

Method 210 can further include a step of replacing the first earthboring tool component with the second earthboring tool component so that light from the light emitting device is directed at it so it is casehardened. The second earthboring tool component can be rotated, if desired, with the earthboring tool casehardening system. It should be noted that method 210 often includes a step of coupling the first and second earthboring tool components together after they have been casehardened with the semiconductor light emitting device. In some situations, the surfaces of the first and second earthboring tool component that have been casehardened are positioned so they face each other. In this way, they experience less wear when they are engaged together.

FIG. 9 is a flow diagram of a method 220 of assembling an earthboring tool component, in accordance with the invention. In this embodiment, method 220 includes a step 221 of providing the earthboring tool component and a step 222 of coupling the earthboring tool component to a rotary system. Method 220 includes a step 223 of providing a mechanical arm which carries a semiconductor light emitting device and a step 224 of directing light emitted by the semiconductor light emitting device to a first surface of the earthboring tool component.

In some embodiments, method 220 includes a step of moving the semiconductor light emitting device along the surface of the earthboring tool component with the mechanical arm. Method 220 can also include a step of rotating the earthboring tool component with the rotary system. Method 220 can further include a step of moving the semiconductor light emitting device, with the mechanical arm, so the light is directed to a second surface of the earthboring tool component.

It should be noted that, in some embodiments, the earthboring tool component includes a channel and the channel is bounded by the first surface. The semiconductor light emitting device can be positioned, with the mechanical arm, so it is outside of the channel and its optical axis is incident to the first surface. However, the semiconductor light emitting device can be positioned, using the mechanical arm, so that it extends into the channel. In this way, the optical axis of the light emitting device is directed at the first surface without using mirrors. The earthboring tool component, if desired, can be rotated while the semiconductor light emitting device extends into the channel.

The embodiments of the invention described herein are exemplary and numerous modifications, variations and rearrangements can be readily envisioned to achieve substantially equivalent results, all of which are intended to be embraced within the spirit and scope of the invention. 

1. A method of casehardening an earthboring tool, comprising: providing a first earthboring tool component; providing a semiconductor light emitting device carried by a mechanical arm; and directing light emitted by the semiconductor light emitting device to a first surface of the first earthboring tool component.
 2. The method of claim 1, further including rotating the first earthboring tool component.
 3. The method of claim 1, further including adjusting, with the mechanical arm, the distance between the semiconductor light emitting device and first surface to adjust the amount of optical power applied to the first surface.
 4. The method of claim 1, further including adjusting, with the mechanical arm, the angle of incidence of the light incident to the first surface to adjust the amount of optical power applied to the first surface.
 5. The method of claim 1, further including moving, along a predetermined path, the position of the semiconductor light emitting device relative to the first earthboring tool component.
 6. The method of claim 1, further including moving the position of the semiconductor light emitting device to direct the light to a second surface of the first earthboring tool component.
 7. The method of claim 1, further including directing light emitted by the semiconductor light emitting device to a second earthboring tool component.
 8. A method of assembling an earthboring tool, comprising: providing an earthboring tool which includes first and second earthboring tool components; rotating the first earthboring tool component; directing light from a semiconductor light emitting device to a surface of the first earthboring tool component.
 9. The method of claim 8, wherein the semiconductor light emitting device is carried by a mechanical arm.
 10. The method of claim 9, further including adjusting the distance between the semiconductor light emitting device and the surface by adjusting the position of the mechanical arm.
 11. The method of claim 9, further including adjusting the angle of incidence of the light relative to the surface by adjusting the position of the mechanical arm.
 12. The method of claim 8, further including replacing the first earthboring tool component with the second earthboring tool component.
 13. The method of claim 12, further including rotating the second earthboring tool component and directing light from the semiconductor light emitting device to its surface.
 14. The method of claim 13, further including coupling the first and second earthboring tool components together.
 15. A method of assembling an earthboring tool, comprising: providing an earthboring tool component; coupling the earthboring tool component to a rotary system; providing a mechanical arm which carries a semiconductor light emitting device; directing light emitted by the semiconductor light emitting device to a surface of the earthboring tool component.
 16. The method of claim 15, further including moving the semiconductor light emitting device relative to the surface of the earthboring tool component with the mechanical arm.
 17. The method of claim 15, further including rotating the earthboring tool component with the rotary system.
 18. The method of claim 15, wherein the earthboring tool component includes a channel and the surface is bounded by the channel.
 19. The method of claim 18, wherein the semiconductor light emitting device extends into the channel.
 20. The method of claim 15, further including moving the semiconductor light emitting device, with the mechanical arm, so the light is directed to another surface of the earthboring tool component. 